1. Field of the Invention
The present disclosure relates to a method for starting a fuel cell system and a starting apparatus for the fuel cell system.
2. Discussion of the Background
Fuel cells produce direct-current energy by an electrochemical reaction between fuel gas (gas mainly containing hydrogen, for example, hydrogen gas) supplied to an anode electrode, and oxidizer gas (gas mainly containing oxygen, for example, air) supplied to a cathode electrode.
Examples of known fuel cells include solid polymer electrolyte fuel cells. The solid polymer electrolyte fuel cells each include a membrane electrode assembly (MEA) including an anode electrode and a cathode electrode which are provided on both sides of an electrolyte membrane composed of a polymer ion-exchange membrane, the MEA being interposed between a pair of separators. A fuel gas flow passage is formed between one of the separators and the membrane electrode assembly in order to supply fuel gas to the anode electrode, and an oxidizer gas flow passage is formed between the other separator and the membrane electrode assembly in order to supply oxidizer gas to the cathode electrode.
During shutdown of a fuel cell, the fuel cell is in a state in which the supply of the fuel gas and the oxidizer gas is stopped, but the fuel gas remains in the fuel gas flow passage of the fuel cell, and the oxidizer gas remains in the oxidizer gas flow passage of the fuel cell. Therefore, in particular, when the shutdown period of the fuel cell is increased, the remaining fuel gas and oxidizer gas permeate through the electrolyte membrane and degrade an electrode catalyst and a catalyst support, and thus the life of the fuel cell may be decreased.
Accordingly, for example, a fuel cell apparatus (fuel cell system) disclosed in Japanese Patent No. 4357836 is configured to be shut down in a state in which an anode flow passage is completely filled with air by supplying air to the anode flow passage from a blower during shutdown of the fuel cell apparatus (refer to paragraph [0021] of Japanese Patent No. 4357836).
Also, the fuel cell apparatus disclosed in Japanese Patent No. 4357836 is configured to purge the air remaining in the anode flow passage during shutdown of the fuel cell apparatus by supplying hydrogen to the anode flow passage at the time of start of the fuel cell apparatus. After purging of the air in the anode flow passage is completed, air is supplied to a cathode flow passage (refer to claim 1 of Japanese Patent No. 4357836).